Speed reducing power transmission



Aug. 29, 1950 w, HENRY 2,520,282

SPEED REDUCING POWER TRANSMISSION Filed Aug. 8, 1947 4 Sheets-Sheet 1 Aug. 29, 1950 E. w. HENRY SPEED REDUCING POWER TRANSMISSION 4 Sheets-Sheet 2 Filed Aug. 8, 1947 1 50 E. w. HENRY 2,520,282

SPEED REDUCING ROWER TRANSMISSION Fi1ed-Aug. 8, 1947 4 Sheets-Sheet 3 /NVENTOE- ERw/N W HENRY H T TQENE Y Aug. 29, 1950 E. w. HENRY 2,520,282

SPEED REDUCING POWER TRANSMISSION Filed Aug. 8, 1947 4 Sheets-Sheet 4 Patented Aug. 29, 1950 UNITED STATES PATENT TOFFICE SPEED REDUCING POWERLTRIANSMFSSIONWH Erwin W. Henry, (Jheyenne, Wye. v Application August s,mistrialNews 4 Claims. (Cl. 74-804)' This invention relates to speed reducing power transmissions" of'epicyclic'gear typeand has as 'an object to provide an improved construction and interrelation of elements" constituting such a transmission. I

A further object of the invention is to provide an improved speed reducing power transmission characterized by "a plurality of simultaneously or alternatively available, coaxial, differential speed, powerbutput elements.

A further object of the invention is to provide an improved speed reducing power transmission characterized by multiple, differential speed, power output elements coaxial with the power input element.

A further object of theinvention is to provide an improved speed reducing power transmission operable to simultaneously effect substantial speed reductions between a power input element and. a plurality of coaxial, independently available, power output elements.

A further object of the invention is to provide an improved speed reducing power transmission effective to convert relatively high speed power input into two or more selectively available, differential, lower speed power outputs with practically negligible operative vibration and a minimum of power loss.

A further object of the invention. is to provide an improved speed reducing power transmission that is efiectively and continuously automatic in the conversion of relatively high speed power input into selectively available, differential, lower speed power outputs.

A further object of the invention is to provide an improved speed reducing power transmission adapted for efiicient operative association with a driven member irrespective of the direction, of driven member rotation.

A further object of the invention is to provide an improved speed reducing power transmission eificiently cooperable with a, reversible driven member in either and both directions of driven member rotation.

A further object of the invention is to provide an improved speed reducing power transmission susceptible of direct connectionto and in operative association. with the driven shafts of various prime mover assemblies.

A further object of the invention is to provide an efiicient and economical construction of co- .operable elements constituting a speed reducing 'a. novel and improved internal. gear construction adapted for simultaneous cooperation with a plurality of planet "gears in a speed reducing transmission unit.

"A further object of the invention is to provide a novel andimproved combination of internal gear and comeshing planet gear tooth form particularly adapted for use in a speed reducing power transmission unit.

A further object of 'the invention is to provide improved diametrically balanced means effective to minimize operative vibration in a speed reducing power transmission unit of epicyclic gear type.

A further object of the invention is to provide an improvedspe'ed reducing power transmission 4 susceptible of extension'and modification in manufacture to provide a variable succession of progressively lower speed,'coaxial, selectively available, simultaneously actuatable, power outputs in axially alined, driven relation with the transmission power input element.

""A further object of theinvention isto provide a speed reducing power transmission in the form of a'compact unit assembly adaptable to a variety of specific installations and applications; to provide a construction for such a unit assembly that is susceptible of economical development through the exercise of established techniques and the use of known tools and facilities; and to give effect to novel and efilcient operative principles in a practical and advantageous manner.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and combination of elements hereinafter set forth, pointed out in my claims, and ustrated by the accompanying drawings, in which Figure 1 is .an end elevation of a typical speed reducing power transmission unit embodying the principles of the invention. Figure 2 is a side elevation ofthe unit shown in Figurel. Figure 3 is a cross section, on an enlarged scale, taken substantially on the indicated line 33 of Figure 1. Figure 4 is a cross section, on a scale somewhat reduced relative to Figure 3, taken substantially on the indicated line 4- 3 of said latter view, Figure 5 is a cross section, on the same scale as Figure 4, taken substantially on the indicated line 5+5 of Figure 3. Figure 6 is a cross section, on the same scale as Figure 4, taken substantially on the indicated line '6-6 of Figure 3. Figure 7 is a cross section, on the same scale as Figured, taken substantially on the indicated line 1+7 of Figure 3. Figure 8 is a cross section, on the samascale as Figure 4, taken substantially on the"indicated" line 88 of Figure 3. Figure 9 is a partial diagram of coacting internal and planet gear elements and relationships significant to and illustrating the method of planet gear tooth form or outline generation. Figure 10 is an enlarged, detail reproduction of the halftooth outline development typical of tooth generation according to the disclosure of the preceding figure.

In the construction of. the illustrated; embodiment ofi theinventi'on, a gear case or unit housing is shown as a drum-like, interiorly-hollow assembly comprised from an axially-short, tubular casing member [5 identically open at its ends and closely similar end plates F8 and H opposed in closing relation with the opposite endsof. themember l5. As a practical structural convenience, the member ends are rabbeted tothe form of annular shoulders adapted to matewith complementary angular shoulders peripherally of the end plates [6 and .11, so that cylindrical pins I58 engaged in parallelism with themember IFaxis through registered holesspa'ced' uniformly andangularly. about the plates lliand' llmargins may, function to clamp said plates to and in endi-closing relation with said member through theagency of nuts l 9:threadedly, cooperating with the exterior ends of said pins. In the constructionshown, the pins |.8 function as certain of'the teetliof an internal gear, ffor which reason said pins. are. spaced'from and inwardly of the member 15. interior wall. and. are centered. on a circle concentric with. said member. dimensioned to function, as the pitch circle of the desired internal; gear. For reasons. that will. hereinafter appear, it is expedient to interpose clamp rings 2,fl between the nuts IQ of. the. pins l8 and the end; plates l'Sf and. I7, surfaces otherwiseengageableby said. nuts,.said clamp rings being annular members of suitable. size formediwith. holes disposedto register withthe pin-accommodating holes of, said end plates. To stiffen the pinv l8 portions spanning. between theplates. IBand I1, and to correlate the angular disposition of. the member. 15.. with that. of said end plates, an annular rib. 2|. is formedron. and projects radially and. inwardly fromthe member. |5,.interior. wall midportion andis intersectedby holes. disposed for. registration with the pin-accommodating holes of "the endplates and hence arranged to be traversed. by the pins. 18.. when. said' member and the associated end plates. are in suitable angular. correlation. Hubs. or bosses. 22' are formed. centrally on and to project. exteriorly fromthe end plates l6..and. I1 and are interiorly recessed to operatively accommodate anti-frice tionbearings 23. coaxial with the member I5, and circular aperturesopen throughthe. end. walls of the hubs or bosses 22 for the accommodation of. power shaft elements rotatively supported by thebearings 23. axially. ofand extending at each end outwardly beyond. the gear. case assembly comprised from the elements. heretofore. described.

Rotatably supportedadjacent one. end by. and engaging through the bearing 23' of the. end plate 1.6, a shaft is journaledaxially of the gear case in a length sufiicient' to project at each end exteriorly of the plates l6 and I1, and'the end of said shaft protruding throughthe plate I6 is suitably worked and equipped; as by means of an axial socket and associated keyway, for convenient connection to and in coaxial driven relation with the power shaft of .a prime mover, such as an electric motor, engine,.or the like. Just inwardly 'ofthe endplate IS; the diameter of the 4 shaft 24 is reduced through an abrupt shoulder against which a double-lobed eccentric block 25 abuts in keyed telescopic relation with the shaft 24 lesser diametric portion. The block 25 is formed to provide axially-ofiset, fixedly-related, identical, circular cams of like and diametrically opposite eccentricity radially of the shaft 24, and a radial flange 26 preferably encircles and ex tends outwardly from the midlength of. the block 25 to. serve as: a. spacer: efiective to separate the elements operatively associated with the opposed cams of said block. Each cam of the block 25 carries and rotatably supports, preferably through theagencyof an anti-friction bearing 27, one of a. pain of like planet gears 28 and 29 thereby mounted on and for independent rotation about the respective cam" and the shaft 24 in spaced parallelism on opposite sides of the spacer 26. The planet gears 28 and 29 are circular with respect to the centers of their supportingcams and are preferably toothed for meshing engagement and coaction with' the fixed internal gear of the'h'ousing or case, said gears being hence so dimensioned'an'dproportioned in relation to the eccentricity of their supporting cams'as'to tangenti'a'lly register the planet gear pitch lines with the internal gear pitchlineportions directly opposed to the. respective gear supporting cam point of'maximum eccentricity; and to operative-'- ly clear the planet gear'tooth addendum circle from. the'internal gear'on thatside of the gear supporting cam opposite. the pointof maximum cameccentricity. As above recited, the centers of the pins 18 define the pitch circle of the fixed internal gear, sections of said pins traversing the gear, case in exposed relation between the end plates I'S'and I1 and the rib- 2 I functioning as, cylindrical'teeth of'a cage-typegear assembly. The internalgear could; of course, be completed through the provision'of a succession of closelyspaced, parallel pins, in. such number and circumferentialspacing as'would provide a gear of the specific character. desired, but a preferred practice involves the use of a relatively limited number of pins 18, sufficient to perfect and maintain the case assembly, and to supply the additional'teeth neededto complete the desired gear in the form of relatively shorter pins 18' spacedly parallelingthe pins l8- and one another in journaled relation through. registering holes intersectingthe end plates [6 and l! and the rib 21 in centeredrelation on the pitch line of the fixed gear; such a structural relation disposing the, pins. I B for end confinement between the clamprings. 20', therebyv inhibiting axial displacement ofIsaid.pins,.and.facilitating ajournaled mounting; for said pins operatively. effective to minimize frictions and'wear. Obviously, the pins (hand l8 comprising the teeth of the, internal gear may, allibe either fixedly or rotatably supportedin the gear case and, when desired, said pins may be of a size less than that desired for the gear teeth and'may each support a rotatably associated wear. sleeve along the length adapted to be engaged by theplanet gears to the end thatfrictions and wear may be accordinglyminimized. The cylindricaljform of the teeth comprising the internal gear points the necessity. for a particular planet gear tooth outline, and such outline, together, with the, method ofits generation, is hereinafter elaborated, but whatever may be the particular form. and" style of the planet and internal gear teeth; the" operative principles" of the invention-will be given effect by the association with aninternal' gear of'given tooth rotationally of its supporting cam in a direction rotation thereabout.

eyseuese number of planet'ge'ars '28 and 29 having; identically, a tooth number less than that of the internal'gear in some multiple of two chosen to accomplish the desired speed r duction or ratio In the illustrated embodiment of the invention,

the internal gear has forty-four teeth and each of the planet gears 23 and 29 has -forty-twoteeth, so that, the end of the shaft traversing the end plate ii being operatively supported for rotation,

each complete revolution of the shaft 24 rolls each of the planet gears in meshed relation with and completely about the internal gear with a consequent two-tooth drive of; each planet gear opposite to that Of shaft 24 rotation, such angular displacement of the planet gears relative to the internal gear being naturally directionally the same for both planet gears, alike inamplitude as evidenced by both planet gears, and uniformly manifest as a fractional progressive displacement of the planet gears as the latter are caused to roll about the internal gear. Thus, in the arrangement shown and described, the planet gears are caused to complete one revolution for T every twenty-one revolutions of the shaft 24 in an opposite direction.

Spacedly adjacent the planet gear 29 and on the side of the latter remote from the gear 28,

a disc-like drive member 30 formed-with an elongate, tubular hub 3| projecting axially from one of its faces is journaled coaxial1y with,'on and for independent rotation about the shaft 24 with the end of its hub 3! remote from said member projected exteriorly of the gear case through and outwardly beyond the end plate I'I.

The'mem- .ber 3E3 is provided to reflect and operatively transmit through its hub 3| angular displacement of the gears 28 and 23 relativeto th unit internal gear consequent upon rotation of the shaft 24, to which end said member 3|] engages simultaneously with. both of the planet gears in a manner to rotate therewith. Efiecting the desired driving connection between the planet gears and the member a plurality of pins 32, in this instance four in number, is fixedly disposed in uniform angular. spacing. on, at like distances radially from the center of, and to project parallel with .the axis of the member 30 from the face. of said member adjacent the gear29, said pins 32 being 'of'uni form length sufiicient to extend through both gears 28 and 29 and preferably being each furnished with a wear sleeve 33 telescoped thereoverand mounted on anti-friction bearings for To operatively accommodate the pins 32 and for driving coaction with the sleeves 33, or exterior surfaces; of said pins,

thewebs of the planet gears 28 and29 are similarly intersected by a seriesof circular holes cor- "responding-in number and angular spacing with said pins. The holes of both gear webs, being alike, are designated by the numerals 34,'and

the holes of each gear web are similarly disposed with their centers on a circle concentric with the associated gear and of a radius equal to the radial offset of the pins 32 on the member'30, and said holes 34 are of like diameters equal'to the effective exterior diameter of a pin sleeve 33, or

equivalent element, plus twice the maximum eccentricity of either throw or lobe of the cam "block 25, so that, the gears-28' and 29 being 'meshed with the unit internal gear to register the centers of their holes 34 opposite the respective cam lobe points ofmaximum eccentricity 'on *acommon diameterof the assembly, the "holes of relationship. I i The gear case or housing is preferably so 6 the; respective gears at all'timespartiaily' register or overlap "to define an 'openchannel or passage adequate :to receiverior accommodate one of the member 30mins in operatively efiective 'b'earing engagement of*=the hole :34 'margins': of; the separate'fgears'against opposit surface areas of the so' ac'commodated sleeve or pin. As so constructed andfarranged, it is readily apparent that the assembly so far described functions in response to rotation ofithe shaft 24:.to angularly displace the gears 28 and: 29*relative to the unit internal gear'in th'eproportion above set forth, 'and' to simultaneously transmit such gear angular "displacement byme'ans of the sleeve equipped pins 32 through the member 30 and hub 3| in" the formbf a slow rotation of said hub about the shaft Zfiexteriorlyof the gear case.

Experience 'in the construction and'assembly ofpra'ctical units embodying the principles of the invention indicates that While the number of pins:.32 efiective to complete the drivelbetweena *g i-ven' planet gear, and associated. memberfdfl ii'ia'y b'evaried and so proportionedto the per-ti nen'ttorque load transmitted thereby, a 'unique relationship of practical significanceappear's to exist; between the numberof suchvpins and 'the number-tor internal gear teeth H l8 and iB ina given unit. If Within the rangeof constructions thus far developed and op'erated,'it is found that unit assembly is feasible and unit operation satis,- factory only when thepin 32- of a'given unit are in a number divisible withoutremainderinto the number of internal gea'r teeth It and I8 present therein. HenceQas --in the illustrated embodiment, an internalgear tooth number divisible without remainder by four requires for practical satisfaction the presence. of iourpin's' -32; an internal gear tooth number divisible without remainder by three would require the presence of three pins 32'; an internal-gear tooth number divisible without remainder by five woul d re quire thepresence of five-pins 32; and similarly throughoutthe normal range of the specified designed' as to accommodate the planet gears "28 and 29 for-"meshed operative engagement "with the internal gear portionbetween the end plate Iii-and rib 2i and to dispose the member 36 {or rotation within the open central area defined by "the rib inner margin, so that a circular cam 35, identical with one of the-lobes of the cam block in the illustrated embodiment, mounted on and ""fix ed for rotation with the member '30 and hub 3! unit adjacent the -member face remote from the gears 28 and 29 may rotatively -mount;and support, through the agency of an antifriction bearing 21,-a single planet gear 36, conveniently identical with-the gears 28 and 29, for rollin engagementabout and in meshedrelation with the internal gear portion between the end plate I! and rib 2| as'said cam rotates with the member 30 and hub 3l unit to which it is attached. The gear 35 is :web-intersectedby holes 3A in number and arrangement functionally identical with the. corresponding ele- "ments of the gears 23and29, anda drivemembar 3? analogous to the member 30 is formed with a coaxial, tubular hub 38 adapted to teleis furnished with drive pins :39 fixedly outstandscopically receive and rotate on the hub3lsand ing in radially-oifset,- axial parallelism from the facei'of the member 31 remote from the. hubl38 to 'accommodation within theholes. 34 of; the gear 751 136,fortthe transmission of gear, 36 angular displacement about its cam 35 to effect rotation of the hub 38 about the hub 3| and shaft 24 in the same manner as the pins 32 operate to convert angular displacement of the gears 28 and 29 into rotation of the hub 3| about said shaft; the said pins 39 being desirably equipped with rotatably associated wear sleeves 33 in the manner and for the purpose shown and described with relation to the pins 32.

Completing the unit assembly for practical use, the hub 33 engages through and is supported for rotation by the bearing 23 of the end plate I! hub or boss ZZand projects exteriorly of the case or housing a distance sufficient to operatively mount and drive a power take-off element, such as a pulley 43, while the hub 3| is journal supported for independent rotation within the hub 38 and about the shaft 24 to extend exteriorly of the ease or housing beyond the outer end of the hub 38 for driving connection with a second power take-off element, such as a pulley 4|, operatively separate from, coaxially adjacent, and characterized by a direction and speed of rotation different from that of the element 40, and the shaft 24 is journal supported for independent rotation within the hub 3| to extend exteriorly of the case or housing beyond the outer end of said hub 3| to there mount and drive a third power take-off element, such as a pulley i2, coaxial with and operatively separate from the elements 40 and 4!, adjacent the latter element, having a. speed of rotation different from that of either element 4!] or 4|, and a direction of rotation the same as that of the element d?! and opposite to that of the element 4|. The speed reducing characteristics of the improved unit being made manifest through planet gear reactions to a fixed circumjacent internal gear, it is essential that the case or housing wherein the internal gear is comprised be secured against any tendency to rotate with the shaft 2 1 or others of the unit elements, to which end the casing member l5 and end plates I6 and 27, either or all, may be furnished with exterior extensions or projections, typified by the structure indicated at 43, adapted for fixed connection to and with related supporting or other immobilized structure to function as torque-resistant base or arm fixtures effective to anchor the case or housing and the associated internal gear and hold the unit against operation-nullifying displacement.

With th elements of the unit assembly constructed, assembled, and arranged as shown and described, the end of the shaft 24 projecting through the end plate |6 fixed coaxially to and in driven relation with the power shaft of a prime mover, and the gear case or housing anchored and held against angular displacement, the improvement is conditioned for practical transmission of power from the associated prime mover. As will be readily apparent, the shaft 24 of the unit assembly is rotatively driven as a consequence of associated prime mover actuation in the same direction and at the same speed as the prime mover power shaft, so that the power take-off 42 on the end of said shaft remote from the prime mover is available for the direct transmission of prime mover power output. As the shaft 24 is caused to rotate, the diametrically opposed lobes of the cam block 25 rotate therewith to uniformly and steadily roll their rotatively-associated planet gears 28 and 29 in constantly-meshed relation with and about the unit internal gear comprised by the pins l8 and l8, the diametric opposition of the like cam lobes and the consequent diametric opposition of the lobe-mounted gears 28 and 29 resulting in a condition of static and dynamic balance inhibitive of adverse operation vibrations, even when the speed of shaft 24 rotation is high. With a planet gear tooth number less than that of the internal gear, each revolution of the shaft 24 results in a planet gear angular displacement, identical for both gears 28 and 29, in a direction opposite to the shaft rotation, and such planet gear angular displacement is transmitted through the pins 32, member 30, and hub 3| to the. power take-off element 4| where it is manifest as rotation of decreased speed and amplified torque in a direction opposite to shaft 24 rotation. Coincident with the differential speed driving of the hub 3| in the manner just described, the cam 35 iscaused to rotate with the member 3|! and hub 3| to slowly and steadily roll its rotatively-associated gear 36 in meshed relation with and about the unit internal gear for a consequent angular displacement of said gear 36, due to the lesser number of its teeth, relative to the internal gear and in a direction opposite to that of cam 35 rotation. At the very much reduced speed of cam 35 rotation, any centrifugal forces deriving from the unbalance of said cam and its gear 36 are insignificant and require no compensation, but should the second stage of speed reduction represented by the gear 36 be utilized in an assembly to which the power input is at abnormally high speed, it is entirely feasible to duplicate the driving cam and given gear in balanced, diametric opposition in the same manner as is described with respect to the first stage of speed reduction. Angular displacement of the gear 36 incident to hub 3| and cam 35 rotation is transmitted through the pins 39, member 31,. and hub 38 to the power take-off element 40 where it is manifest as a relatively very slow, correspondingly very high torque, steady rotation of said element 40 in a direction the same as that of element 42 rotation, thereby completing a series of simultaneous]y-operating, selectively-available, closely-adjacent, coaxial power take-offs or outputs coaxial with and on the side of the unit assembly remote from the power input.

Obviously, the unit assembly may be extended or modified at the time of its manufacture to accomplish a succession of simultaneous speed reductions in such number and differential speed proportions as may be desired for particular purposes, one of the outputs or power take-offs of each such embodiment having speed and torque characteristics identical with the associated prime mover. Representative of the relationships obtainable through units of the type shown and described, a forty-four tooth internal gear reacting with forty-two tooth planet gears in a two-stage reduction is productive of a first stage speed reduction of twenty-one to one, a second stage reduction of twenty-one to one with respect to the first stage output, and consequently a second stage reduction of four hundred and forty-one to one with respect to the input speed. Thus, given a prime mover power shaft speed of 1750 R. P. M., the first stage reduction of the unit would be manifest as a speed of 83 /3 R. P. M. in the take-off element 4| and the second stage speed reduction of the unit would be manifest as a rotational speed of just slightly less than 4 R. P. M in the take-01f element 42. Through variations in the tooth numbers of the internal gear and planet gears within the structural and'operative' limits-peculiar to the structure of the unit, a range of speed differentials characterizing the power outputs of the unit may bedeveloped to meetan almostinfinite number of particular operative requirementswith reference to the known powershaft speed of a'selected prime mover.' r A novel characteristic of the improved unit being the use of a spaced, parallel succession of cylindrical elements centered on a circle-to -constitute the teeth of a cage-type gear whereof said circle is the pitch line and'wherewith the external teeth of eccentrically-related, interiorly+ disposed, spur gears of lesser diameter are intended to mesh, a particular-spur :gear 17001711 form or outline is required to effect? the desired coaetion in each selected combination-spi gear tooth numbers, pitch, consequent diameters and cage gear tooth size, hence a characteristic spur gear tooth form and a reliabl'emethod applicable to generate the specific outline-pertinent to a given set'of conditions are material to"a comprehensive disclosure of the invention. -To be operatively and satisfactorily effective, the teeth of the planetor-spur gears must have an o u-tline form smoothly coactable with the "cylindrical tooth elements ofthe cage geanwithout wedging or binding effect, in every" relation of a given spur gear tooth with the successive cage gear teeth'resultingirom rolling 'of theeccentrically-mounted spur gear in "meshed engagement about and-within the cage gear,-which"re-- quirement gives merit'to a spur gear-toothbutline determination in the --manner and through application of the method-*eXemplified-by Fig ures 9 and '10.

"Each spur and cagegear; combination-ofg-the type employed in the improved unit is -characterized by certain -predeterminedorassumed dimensional data pertinent to determination ofan appropriate spurgear tooth-outline for-the combination. Such data'willinclude the tooth pitch orspacing,- alike for both-gears, and the number of teeth for eachgean-whichiactors control and determine-the respective gear-pitch circle diameters and the eccentricity of 'spun gear mounting, as well as-the cage-gear cylindrical tooth diameter. With these data, :assumed as hereinafter specified, the appropriate spur gear tooth out ine may be convenientlyand-pre cisely developed through correlation of the: suc-v cessivecage gear tooth positions with a single spur gear tooth zone as represented by-the diagrams of Figures -9 and 10-and hereinbelow ex-.

l lained. T In the ms, itis assumed that.the-.a

gear teeth are cylinders of three-eight inch di-. ameter, that the cage gear 'has .fortyl-four-lteeth and the spur gear fortyetwo teeth; and thatthe.

tooth pitchis three-quarters of\ an- .inch, i-'from Which assumptions it follows that thecage gear.

Will have a pitch circle diameter of ten and one-, half inches, very nearly, the s'pur gear "at pitch circl diametercf ten and ione fortieth inches approximately, and that 'the radius of eccentricity. oi the spurgear mounting relative toithe;cages gear, being one-half the. difference between the pitch circle diameters, will. approximate nineteen: eightieths of an inch .These data are, trans lated into a scale diagramfllby scribing anarc' C of properradius about a center-IO to represent the cage gear pitch circle, scribing as'econd'am s eitherseparate from or, internally tangenlifio t e a C, of per radiusabouta center ,Qi, .t0

represent the spur gear. pitch circle, demarking and successively identifying pitch distances from a common point along each of the arcs C and S, as indicated by the designations 0-4 and '-sl=, et sequentia,and scribing a circle E about the center -p 'with; a; radius equal to one-half the difierence between the pitch circle diameters. From thesuccessive pitch distance points sl', et seq., of the are S, radii are extended through the center 0' to intersect the remote side of the circle E to mark, by such intersection, spaced points e l, et seq.', constituting a succession of centers for-subsequent use. With a compass set to the radius of the arc C and progressively and successively centered in the points e-l, et seq;, of the circle-E, non-uniformly spaced arcs y-l, et'seq eare scribed exteriorly of and across the zone of-the arc-S' between the origin point of pitch distance demarcation and ;the point s|'=, and a point a: is then located on each of the arcs ytoserve asa center for-the scribing of-a circle 2 representing acage tooth eireumference.;---For the location of-=the points on--the respective arcs y-;---the successively designated pitch distance points-of both-arcs C and- S-are-utilizedw-With compass or dividers, the straight'line length from the origin point of pitch distance demarcation on -the:arc-C ismeasuredto any given pitch dis tancepoint o-n-1-said-are and th -,length so determinedtislthen used as a radius centered at one end onrthe are S pitch distance point corresponding in numbers to the --arc G point wto:-which thc length-r twast-measurediandis swung about such centers, to-intersection at its other. end withs-the y arctof number, corresponding with the, center point-employed, thereby establishingth ,des-ired pei monqth eparticularta e-y; hr u h pB- titiousapplication ottheeproceduijejust outli d, points zv,. -aret p etes to h arcs yeta-r p al ii the centersof the cage gear ,teeth a -successively point, oi pitch distance demarcation origin and, 656. V fiDOi ifiWQ -i Q Fpi c l zt n ngth determines.thehalf outlineiofla spur g r toth s uitedgto effectthe coactio-ndesired.

From the foregoing-"it is readily appa" separately '01" simultaneously available to drive;

apparatus "and mechanisms," or differential speed elements thereof, of an infinite variety. of (dnj structions and. purposes. The ."improvement' is. particularly adapted for mounted associatioion; and in 'direct drivenrelation withthe,powershalt of an "electric motor fordilferential speed power. output inalinement with the power shaftaxis and in anchored relation ofthe unitcase or. housing with. the. motor structure, thereby. eiiectively, converting the motor to mu1tispeed.dri vingpur r poses with a minimum .oflinstallation problems. and iwith advantageous adaptability of the "re? are the improvement is susceptible of manufacture sulting power combination. The balancing of the higher speed reduction stage or stages of the improved unit accomplished as hereinabove set forth precludes the development of destruction and disadvantageous vibrations incident to unit operation and contributes to the efiiciency, long life, and smooth operation of the unit at low noise level, and the novel gear tooth-combination characteristic of the improvement is material to economy of unit manufacture and efficiency of unit operation.

Since many changes, variations, and modifications in the specific form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. A speed reducing power transmission comprising a fixedly-mountable housing assembly enclosing a fixedly-related, axially-elongate, internal gear, a driven shaft connectible with and for rotation by a source of power journaled in and axially traversing said assembl concentrically of said gear, a sleeve hub telescopically coaxial with and rotatable about saidshaft through the assembly wall remote from the shaft power input end, planet gear means eccentrically journaled on said shaft in constant-meshed relation with said internal gear, driving connections between said planet gear means and hub effective to manifest angular displacement of the former as corresponding rotation of the latter, asecond sleeve hub telescopically coaxial with and rotata ble about said first hub through the assembly wall, planet gear means eccentrically journaled on said first sleeve hub in constant-meshed relationwith said internal gear, driving connections between said latter planet gear means and second hub effective to manifest angular displacement of the associated planet gear means as corresponding rotation of said second hub, a simultaneouslyavailable power take-off means on the adjacent coaxial ends of said shaft and hubs, wherein'said housing assembly is comprised from an openend tubular member and centrally-apertured, circular plates clamped to and in closing relation across the member ends by means of bolts engaging through said plates in inwardly-spaced parallelism with the member inner cylindrical wall to constitute teeth of said internal gear, and is equipped with means for anchoring the unit against rotation about its axis.

2. A speed reducing power transmission comprising a fixedly-mountable housing assembl enclosing a fixedly-related, axially-elongated, in ternal gear, a driven shaft connectible with and for rotation by a sourc of power journaied in and axially traversing said assembly concentrically of said gear, a sleeve hub telescopically coaxial with and rotatable about said shaft through the assembly wall remote from the shaft power input end, planet gear means eccentrically journaled on said shaft in constant-meshed relation with said internal gear, driving connections between said planet gear means and hub effective to manifest angular displacement of the former as corresponding rotation of the latter, a second sleeve hub telescopically coaxial with and rotatable about said first hub through the assembly wall, planet gear means eccentrically J'ournaled on said first sleeve hub in constantmeshed relation with said internal gear, driving connections between said latt r planet gear means and second hub efiective to manifest angular displacement of the associated planet gear means as corresponding rotation of said second hub a simultaneously-available power take-off means on the adjacent coaxial ends of said shaft and hubs, wherein said housing assembly is a. cylindrical unit anchorable against rotation about its axis, and said internal gear is comprised from a succession of like cylindrical elements uniformly spaced apare angularly about, at like distances radially from, and parallel to the axis of the assembly to traverse the full length of the latter in inwardlyspaced adjacency to the assembly inner-cylindrical wall.

3. A speed reducing power transmission comprising a fixedly-mountable housing assembly enclosinga fixedly-related, axially-elongated, internal gear, a driven shaft connectible with and for rotation by a source of power journaled in and axially traversing said assembly concentrically of said gear, a sleeve hub telescopically coaxial with an rotatable about said shaft through the assembly wall remote from the shaft power input end, planet gear means eccentrically journaled on said shaft in constant-meshed relation with said internal gear, driving connections between said planet gear means and hub efiective to manifest angular displacement of the former as corresponding rotation of the latter, a second sleeve hub telescopically coaxial with and rotatable about said first hub through the assembly wall, planet gear means eccentrically journaled on said first's'leeve hub in constant-meshed relation with said internal gear, driving connections between said latter planet gear means and second hub effective to manifest angular displacement of the associated planet gear means as corresponding rotation of said second hub, a simultaneously-available power take-off means on the adjacent coaxial ends of said shaft and hubs, wherein said internal gear is a cage of uniformly spaced parallel, cylindrical, tooth elements concentrically about the driven shaft in fixed relation within and to bridge between opp0- site-ends of the housing assembly, and the planet gear means comprises, in each instance, at least one spur gear toothed in a number less than that of the internal gear to roll in meshing co-action interiorly of the latter about a circular cam eccentrically fixed to a driving element concentric with the internal gear.

4. A speed reducing power transmission comprising a fixedly-mountable housing assembly enclosing a fixedly-related, axially-elongated, internal gear, a driven shaft connectible with and for rotation by a source of power journaled in and axially traversing said assembly concentrically of said .gear, a sleeve hub telescopically coaxial with .and rotatable about said shaft through the assembly wall remote from the shaft power input end, planet gear means eccentrically journaled on said shaft in constant-meshed relation with .said internal gear, driving connections between said planet gear means and hub effective to manifest angular displacement of the former as corresponding rotation of the latter, a second sleeve hub telescopically coaxial with and rotatable about said first hub through the assembly 13 14 corresponding rotation of said second hub, a REFERENCES CITED simultaneously-available power take-oft means The following references are of record in the on the adjacent coaxial ends of said shaft and m f t hubs, wherein the planet gear means of higher 8 0 18 pa speed reduction stages comprises a pair of iden- UNITED STATES PATENTS tical spur gears toothed in a number less than Number Name Date that of the internal gear to roll in simultaneous. Re. 17,811 Braren Sept. 23, 1930 diametrically-opposed, meshing coaction inte- 2,170,951 Perry Aug. 29, 1939 riorly of the latter and in closely-spaced, parallel 2,303,365 Karlsen Dec. 1, 1942 adjacency about like, diametricallyopposed, cir- 10 2,382,482 Henry Aug. 14, 1945 cular cams, eccentrically fixed in parallel adjacency to a driving element concentric with the FOREIGN PATENTS internal gear, and the driving connections be- Number Country Date tween said planet gear means and correspond- 361,015 Great Britain V 1931 ingly-rotatable sleeve hub correspondingly and 15 simultaneously engage both said spur gears.

ERWIN W. HENRY. 

